This research proposes to construct from data collected over a spectrum of clinical uses an overview evaluation of the clinical efficacy and cost effectiveness resulting from the introduction of MR imaging technology in a single metropolitan community. An aggregate analysis will summarize measures of diagnostic accuracy, diagnostic impact efficacy, treatment efficacy, and cost effectiveness. The data in the individual protocols will be collected prospectively and the performance of MR compared to competing imaging techniques using a randomized design in which patients will receive both modalities in random order, with equal clinical information provided and with a systematic approach to establishing the "true" final diagnosis. The "natural history" of MR use in an entire community will be documented including objective determination of the clinical problems for which MR provides no incremental benefit and those in which it is considered efficacious and cost effective. Cost data will be derived from an MR center established as a community research project in which the real costs of providing MR examinations at full levels of utilization will be available. Such data should assist in the rational planning for the introduction of this new expensive diagnostic technology elsewhere.